AKI Flashcards
Drug dosing in AKI
- Decision to dose adjust medications should be a clinical decision based on CrCl, UO, and suggested dosing guidelines
- Calculate CrCl and review UO daily
- Dose reduce based on suggested guidelines
- Consider serum drug concentrations
- Dose adjust back up when renal function recovers
AKI pt evaluation steps
- Discontinue nephrotoxic medications
- Identify cause of AKI
- Treat AKI
- Renally dose adjust medications
Post renal AKI diagnosis
- Renal imaging
- UA: Hematuria, crystals
- BUN:SCr <15:1
- FeNa > 1%
- No daily change in SCr
- Anuria
Be able to identify and treat different types of AKI
Know how to calculate a CrCl and UO
Be familiar with prevention strategies
Know common medication nephrotoxins
Dose adjust medications in AKI
Urinary Analysis
- Hydration
- Color
- Dark yello=dehydrated
- Specific gravity
- >1.020 = dehydration
- Color
- Infection
- WBC
- >50= infection
- Leucocyte esterase
- Production of neutrophils
- 1+,2+, 3+ = infection
- Nitrites
- made by bacteria
- Positive= infection
- WBC
- Kidney Function
- Protein, 1+,2+,3+ = intrinsic renal failure
- RBC, Positive = Traumatic catheterization, tumor, nephrolithiasis
- Casts
- Different types (hyaline, granular)
- Positive = intrinsic renal failure
- Crystals
- Different types (uric acid, calcium oxalate)
- Positive = tumor lysis syndrome or nephrolithiasis
Types of Acute Kidney Injury
Prerenal
Intrinsic
Postrenal
Prerenal AKI
- Occurs prior to the kidney
- Reduction in blood volume
- Reduction in bloodflow to the kidney
- Hypotension
- Sepsis
- Heart or liver failure
- Bleeding
- Renal thrombosis
AKI definition
Decline in?
Increase?
Increase?
- Abrupt reduction in kidney function
- Decline in urine output
- Increase SCr
- Increase BUN
Post renal failure tx
- Remove obstruction
- Nephrolithiasis- lithotripsy
- Tumore= Surgery
- Stricture = urinary stent
- BPH = doxazosin, tamulosin, finasteride
- Hydronephrosis
- Nephrostomy tube
Prerenal Failure Tx
- Restore blood volume
- IV fluids- aggresive rehydration with normal saline or balance solution
- Discontinue diuretics
- Restore blood flow
- Blood - indicated in bleeding situations
- Treat the underlying cause conditions (heart failure, sepsis)
- Discontinue and limit nephrotoxins
Types of intrinsic AKI
ATN and AIN
CRRT
- Indicated when blood pressure too low to tolerate HD
- Continual removal of fluids and solutes so more resembles actual kidney function
- Differ in way the solute is removed
Diagnosing prerenal AKI
- Pt hx, N/V, diarrhea
- Dry mucous membranes, decrease jugular venous distension
- UA: Dark yello, high specific gravity
- BUN:SCr > 20:1
- Urinary Na < 10
- FeNa < 1%
- Oliguria
- Rapid change in SCr with tx
AKI symptoms
- Fluid overload
- SOB
- Peripheral edema
- wt gain
- Urinary Changes
- Decreased or painful urination
- Change in color or odor
- Uremia
- N/V
- Itching
- Fatigue
- Confusion
- Situation
- Flank pain
- HA
- Arthralgia
AKI complications
- Fluid overload
- Pulmonary and peripheral edema
- IV bolus loopd diuretics –> Continuous infusion loop diuretics —> hemodialysis
- Electrolyte abnormalities
- Increase K, Phosphorus, magnesium
- Hyperkalemia most common and concerning
- Blood glucose irregularities
- Hyperglycemia common due to impaired glucose homeostasis and metabolic stress
- Insulin eliminated by the kidneys so may result in hypoglycemia
Drug dosing in AKI
HD
and
CRRT
- Assume little to no UO
- Drug elimination dependent on filter type, flow rate, amount of time on HD and drug characteristics
- Molecule size, protein binding, ionized form
- Dosing different for each medication
- Bolus dosing daily or 3 times/week after HD
CRRT
- Dependent on flow rate but usually assume normal renal function with no drug adjustment
ATN -
Nephrotoxic meds
- ACEs
- ARBs
- NSAIDs
- Amnoglycosides
- Vancomycin
- Amphotericin B
ATN- Rhabdomyolysis
Rhabdomyolysis
- breakdown of muscle cells releases damaging proteins into systemic circulation
- Seen by an increase in CPK and myoglobin
- Myoglobin specifically damages kidneys
- Serum myoglobin level useful in diagnosis
- Treat with fluids such as normal saline or sodium bicarbonate
Risk factors for AKI
- Male
- AA
- Advanced Age
- CKD
- DM
- Heart or Liver Disease
- Surgery
- Sepsis
- Hypotension
- Volume depletion
- Diarrhea
- Vomiting
- Dehydration
- Medications
AKI monitoring
- Daily wts
- Fluid intake and UO
- Daily serum creatinine
- daily serum electrolytes
- Vital signs
- Symptoms (edema)
Post Renal AKI
- Occurs after kidney
- Caused by an obstruction between kidney and urethra
- Nephrolithiasis
- Uric acid crystals
- Tumor
- Stricture
- BPH
Type of renal replacemen
Hemodialysis
Rapid removal of fluids and solute
Performed daily in acute setting or 3 x
common complication hypotension
AKI treatment goals
- Restore renal function to baseline
- Identify the cause
- Reverse the cause
- Limit damage
- treat symptoms
- Manage complications
Modification of Diet in Renal Disease (MDRD)
- Calculate an eGFR
- Better estimates renal function
- Utilized to stage renal failure
Indications for renal replacement therapy
AEIOU
- Acidosis
- Electrolytes
- Intoxication
- Overload
- Uremia
ATN
Contrast Induced Nephropathy
- Dye causes free radical formation which is directly toxic to the kidneys
- SCr increase 2-5 days after contrast exposure
- Prevention is key
- Normal saline or sodium bicarb infusion
- N-Acetylcysteine
SCr
- Must know pts baseline
- Trend in SCr more important than acutal level
- Lag in SCr change by 1-2 days from original insult
- Use of GFR equations limited as these assume stable renal function
Urine Output
- Most acute marker of change in renal function
- Conern when <0.5 mL/kg/hr
- Complicated by volume status, diuretic use and obstruction
- Nomentclature
- Nonoliguric is > 500 ml/day
- Oliguric <500 ml/day
- Anuric <50 mL/day
Acute Interstitial Nephritis AIN
- Delayed hypersensitivty rxn
- Tubular and Interstitial inflammation
- Symptom triad, Fever, Rash, Urine Eosinophils
- Medications most common cause
- beta lactam antibiotics
- NSAIDs
- Trimethoprim/ sulfamethoxazole
Review
- Normal kidney function markers
- Definite, detect and classify AKI
- Types of AKI
- Diagnosis and tx
- Prerenal, intrinsic and postrenal
- Renal replacement therapy
- Complications of AKI
- Drug dosing in AKI
- AKI prevention
Fractional Excretion of Sodium
- Reflection of ability of kidney to concentrate urine
- Not accurate if recent diuretic use
AKI Markers and lab testing
- SCr
- UO
- Urinary Analysis
- Urine Electrolytes
- Renal imaging
Urine output criteria
Risk
injury
Failure
Loss ESRD
- UO < 0.5 ml/kg
- UO < 0.5 ml/kg x 12 hours
- UO < 0.3 ml/kg x 24 hours or anuria x 12 (oliguria)
- Persistent ARF = complete loss of renal function > 4 weeks
- ESRD
Kidney Function Markers
Urine Output
Normal Output?
How to calculate?
- Best marker of urine function
- Normal urine output = 0.7-1 ml/kg/hr
- To calculate determine amount of urine output and divide by the pts weight and time period
Kidney Function Markers
Serum Creatinine
SCr < 1
Affected by age, gender, muscle mass, diet and hydration status
Some medications may increase
Intrinsic AKI
- Direct damage can be due to the glomerulus or tubules
- Kidney injury a result of
- Ischemia
- Toxins
- Medications
- Contrast dye
- Proteins (myoglobin)
AKI classifications
Staging Criteria
Types of Staging systems
- Staging
- SCr change for baseline
- GFR change from baseline
- Urine output over specified time period
- Systems
- Risk, Injury Failure, Loss of Function and ESKD (RIFLE)
- Acute Kidney Injury Network (AKIN)
- Kidney Disease: Improving global Outcumes (KDIGO)
glomerular filtration rate
equation
(140-age) x wt (kg)
/
72 x SCr
if female x by 0.85
GFR Criteria
Risk
Injury
Failure
Loss
ESRD
- Increased creatinine x 1.5 or GFR decrease > 25%
- Increased creatinine x 2 or decrease >50%
- Increased creatinine x 3 or >75% decrease or creatinine > 4 mg per 100 mL
- Persistent ARF = Complete loss of renal function > 4 wks
- ESRD
Renal imaging
Renal ultrasounds
Abdominal CT scan
Intrinsic renal failure treatment
- Discontinue offending agent
- IV-fluids- normal saline or balanced solutions
- Limit nephrotoxins
Normal Renal Function
A WET BED
- A- Acid/base balance
- W-Water balance
- Electrolyte balance
- Toxin Removal
- Blood pressure control (Renin)
- Erythropoietin production
- Vitamin D activation
Intrinsic AKI diagnosis
- UA: Protein, granular casts, eosinophils
- BUN:SCr < 15:1
- FeNa > 1%
- Slow change in SCr with tx